Hysteresis for anisotropic ±J Ising square lattices

It is known that ±J square Ising lattices exhibit hysteresis in the isotropic case emulating some general behavior of spin glasses. On the other hand, some experimental curves of hysteresis in real spin glasses show additional features not explained by simulation on isotropic systems. In the present work, we explore the possibility of explaining some of these features by introducing anisotropic ±J exchange interactions so they are stronger along one direction by an anisotropy factor f (square symmetry is broken), which is varied in the interval 1-8. For each sample, hysteresis cycles are found varying temperature by means of Monte Carlo method. The analysis is extended over many samples for each size searching for average magnetization values under different realizations. Two interesting properties are established in this paper: (a) Loops break into sub loops; (b) Energy loss per cycle (area within the hysteresis loop) tends to increase with f, which is an indication for a more stable spin-glass phase in the presence of anisotropy. Comments comparing these results with experiment are also included.